- /* POSIX requires strerror (0) to succeed; use of "Unknown error" or
- "error 0" does not count as success, but "No error" works.
+ /* POSIX requires strerror (0) to succeed. Reject use of "Unknown
+ error", but allow "Success", "No error", or even Solaris' "Error
+ 0" which are distinct patterns from true out-of-range strings.